Outer Limits 4x4 Board

Okie dokies, I picked up my 4runner today and had a few teething problems on the way home. The only major one is the gear box makes a lovely whining noise under excelleration and when slowing down it pops out of gear (mainly 1st and 3rd gears). Is this a common prob?? A mate rekons it may be a syncro prob?

Anyway any light would be appreciated, im happy to get another box if needed but if its a common prob ill be happier to fix it.

Its a 89 model 2.8l diesel 4runner.

What is the oil level ? how old is the oil?
Check the pivot sockets at the bottem of the gear lever, the bush might be warn and not letting it fully selecting gear
Change the oil
If it is howling it could need reconditioning
The G52 does not generaly have a problem if driven normaly